An explosion in an underground station in St Petersburg has killed at least 10 people, according to Russian media reports.
The Tass and Interfax agencies reported up to 50 people have also been injured in the blast between Sennaya Ploshchad and Tekhnologichesky Institut stations.
The head of Russia’s National Anti-Terrorist Committee said an explosive device was later found and made safe at another station nearby.
Prime Minister Dmitry Medvedev said in a Facebook post that the explosion was “terrorist attack”.
An anti-terror investigation has been opened, but other possible causes are being investigated too.
Images posted on social media show the station filled with smoke and a train carriage with its doors blown out.
The entire St Petersburg underground network was shut after the incident and Moscow metro officials are said to be introducing extra security measures as a result.
2. Video after the explosion. #SaintPetersburg#StPetersburgpic.twitter.com/IoIgQ9Av0A
— Amarnath Amarasingam (@AmarAmarasingam) 3 April 2017